Fish Yawns, Gun Defense, and Runoff Reactions

Today I Learned:
1) Fish are generally believed to yawn (they do a thing that looks like yawning, which is usually but not always interpreted as a yawn). Fish sometimes use yawns as an aggressive or territorial signal, but they also seem to just... do it, sometimes.

2) Guns are used a LOT in self-defense in the US. This is a big, politically-charged topic, so reading Wikipedia is probably not giving me the full story. Furthermore, different groups have come up with WILDLY different estimates of defensive gun use, but they're pretty much all far above what I would have guessed. Technically, the range of possible rates of defensive gun use range from 127/year (not a typo) to 33.1 million/year. That's about the highest variance I've seen in any estimate not involving things like Dyson spheres and bagels.

33.1 million per year seems ludicrously high -- I'm pretty sure fewer than one out of six Americans uses a gun in self defense each year -- but even the more accepted lower estimates are pretty high. One of the lowest was an estimate by a professor at the Harvard School of Law at 55,000-80,000/year. For reference, that's 5-8 times higher than the annual number of *deaths* caused by guns in the US. Another interesting statistic: in cases of defensive gun use, the gun is actually fired somewhere between 1/4 and 1/3 of the time.

3) We have a thing in our lab where we prepare extracts from bacterial cells, and one of the steps involved is an 80 minute incubation of the freshly-prepared extract at 37 C. We call this a "runoff reaction", and it's supposed to be the step in which genomic DNA is degraded. Today I learned why that step is called a "runoff reaction". This kind of step is used in other cell-innard-extracting techniques to get rid of lingering RNA strands that might still be bound to ribosomes, which makes them temporarily inaccessible to degradation machinery. The incubation step gives the ribosomes a chance to finish translating out protein, freeing the RNA for degradation... since the ribosomes literally run off the end of the RNA, it's a "runoff reaction". Thanks to Anders Knight for this epipheny!